This is the worst accident to hit Russia's busiest subway. Nineteen people died at the scene, while another died of injuries in hospital, a health ministry spokesman said in televised remarks. Nearly 130 people have been hospitalised.

The train derailed between Park Pobedy and Slavyansky Boulevard metro stations. Rescue teams are working to rescue about five people believed to be stuck in a carriage underground.

'Train was just pulled apart'

One witness, a young man in a polo shirt, said in televised remarks: "I got into the carriage and after about 20 seconds, the light went out and the train was just pulled apart. I was just thrown into the centre of the carriage."

"We climbed out of the carriages and we saw a blockage, men took hammers and pliers and broke it down and we walked on. The train was smashed, the chassis was just pulled apart," he said.

Authorities said it would take 24 hours to deal with the aftermath of the accident.

The Investigative Committee said that preliminary information showed the accident was due to the train braking abruptly because of a false alarm triggered by a supply voltage dip.

Moscow’s metro is considered one of the world’s busiest and carries some nine million people every day.